Alkali-resisting phenolic aldehyde siccative composition and process of making same



o to, say, 150

Patented Dec. 27, 1938 UNITED STATES ALKAIJ-RESISTING PHENOLIC ALDEHYDESICCATIVE COMPOSITION AND PROCESS OF MAKING SAME John B. Rust, Orange,N. J.,

assignor to Ellis- Foster Company, a corporation of New Jersey NoDrawing.

8 Claims.

This invention relates to phenolic resin siccative compositions and aprocess of making same, having as an object the production of varnishand lacquer solutions capable .of forming airhardening films which arerelatively alkali resisting.

In varnish making practice an oil-soluble phenolic resin customarily ismixed with a drying oil, for example, tung oil, and the mixture isheated to a high temperature, usually from 230-280 C. or higher, andmaintained at this temperature until the varnish mixture has thickenedto the desired viscosity, then is thinned with a suitable solvent. Theobject of heating the resin and oil to a high temperature is to renderthe varnish mixture soluble in mineral spirit solvent and the varnishfilm free from frosting, crow-footing or wrinkling. For instance, iftung oil and an oil-soluble phenolic resin are heated C. until the resindissolves then thinned with V. M. 8: P. naphtha, the varnish mixturewould not be entirely soluble yielding a cloudy solution. However ifthis samevarnish mixture is dissolved in xylol the solution is clear butthe film from the solution upon drying would wrinkle and become coveredwith a network of fine lines. Thus, in the ordinary varnish kettlepractice of making such varnishes, paints or enamels, the purpose ofheat-treatment of the oil-resin mixture at a high temperature ismerelyto thicken the composition to the correct viscosity, to increase itssolubility in mineral spirit solvents, to prevent the varnish film fromcrowfooting, frosting or wrinkling and to increase its resistance tofilm destroying agents. If tung oil and oil-soluble phenolic resin areheated at a low temperature, say, 100-150 0., little or no thickeningtakes place in several hours and the varnish is not entirely soluble inmineral spirits and a film would crow-foot and wrinkle upon drying. Whenheated at a high temperature the varnish compositions probably thickenmainly through a polymerization of the "drying oil. Thickening may alsobe due to a slight extent to the reaction of-a resin molecule with amolecule of drying oil. I

The present invention, radical departure from the old practice. Theprocess comprises soluble phenolic resin with a drying oil in thepresence of a catalyst at a low temperature. When I speak of lowtemperatures I mean temhowever, represents a varnish kettle peraturesfrom about 90 to 1601C. Any acidcatalyst may be used but I prefer to usecatalysts which are soluble in both the drying oil, resin reacting anoil- Application December 23, 1935, Serial No. 55,842

and oil-resin mixture; are easily removable from the oil-resin reactionproduct either by washing or volatilization; will not darken theresin-oil reaction product; will not polymerize, gelatinize or char thedrying oil. In general oxalic acid fits these requirements, although Imay use other acids such as dichloracetic acid, phosphoric acid,hydrochloric acid, p-tolu'ene sulphonic acid, sulphuric acid ormonochloracetic acid. The proportion of the catalyst depends upon itsstrength, although in general from 2% to .5% in the case of oxalic acidwill suilice. Hydrochloric acid, being a much stronger acid andtherefore inclined to gelatinize and cause darkening, preferably shouldnot be present in quantities over .5%. The proportion of drying oil tooil-soluble phenolic resin in this invention is not limited but may varyfrom, say, 1 part of drying oil to '2 parts of resin to 1 part of dryingoil to A of a part of resin.

Although I may use any drying oil, I prefer tung oil or oiticica oil orsome fatty oil containing conjugated double bonds, since this type isthe most reactive. The advantages of the present process are theproduction of thickened varnish mixtures at a low temperature which arefast to light, dry rapidly, are substantially alkali, acid, water andweathering resisting.

As I have stated, in the usual varnish kettle method of making varnishesthe thickening of 'the oil-resin mixture probably is due-mainly to apolymerization of the drying oil itself. How: ever in the presentprocess thickening of the oilresin mixture seemingly is due to areaction of a resin molecule with a drying oil molecule. This isindicated by the fact that when the resin and oil mixture'is heated at,say, 120 0. without a catalyst no thickening is. apparent in severalhours. If, however, a catalyst is included thickening results upon 5 to15 minutes of heating. Furthermore if the drying oil and catalyst areheated together at120 C. without the resin no thickening occurs. Hence,the products of the present invention are new and distinct from thoseobtained by the usual varnish kettle process, as will further beillustrated hereinafter.

Any oil-soluble phenolic resin may be used as thisthe resinousconstituent of the process of invention. For instance, I may employ anoilsoluble xylenol-formaldehyde resin, resorcinolketone resins,naphthol-formaldehyde resins, ptertiary butyl phenol formaldehyderesins, cresolacetaldehyde' resins or p-hydroxy diphenyl formaldehyderesins. Furthermore mixtures of drying Oils such as tung oil andoiticica oil, tung However, these gelled f ther.

oil and linseed oil, tung oil and soy bean oil, or oiticica oil andperilla oil may be used instead of tung or oitlcica oil alone. It ispreferable to use either tung or oiticica oil as one of the drying oilcomponents since these latter oils are much more reactive in the processof the present invention with phenolic resins than the linseed orperilla oil type of drying oil.

The incorporation of the drying oil with the oilsoluble phenolic resinin the presenceof an acid catalyst is preferably carried out at'theserelatively low temperatures since the reaction can thus be far bettercontrolled. If the reactionv is allowed to proceed soluble, infusibleand too far mineral spirit-ingelled masses will result. masses areuseful for the production of linoleum-like materials when mixed withcork or other fillers and for various other purposes.

The products of the present invention are more resistant than thevarnish compositions made by the usual high-temperature varnish kettlemeth od. This is probably due to the substantially complete reactionwhich takes place between the resin and drying oil in the presentprocess. For instance, if an oil-soluble xylenol-formaldehyde resin ismade into a gallon varnish according to the usual method and a film ispoured onto a glass plateand allowed to harden for several days'thenimmersed in a 5% caustic soda solution the film is complete y eaten awayin about 18 hours. .However. if the same xylenolformaldehyde resin isheated with tung oil in the presence of 2% oxalic acid catalyst inproportions necessary to form a 25 gallon varnish and afilm of thevarnish poured onto a glass plate; dried several days. then immersed incaustic, the film does not whiten or blister in 36 hours and is onlyaffected after 98 hours of immersion. This represents about a 500%increase in alkali resistance. Although this is. a spec fic example.other resin varnishes made by the present process also show very markedincrease in chemical resistance.

The following are examples given better to illustrate the process andproducts of this invention; all pro ortions being in parts by weight.

Resin .4. 700 parts of a commercial mixture of meta and para cresols areheated to 100-110 C. with 70 parts of oxalic acid and acetaldehyde gasis passed through the melt for 8 hours at a volume equivalent to 34parts of acetaldehyde per hour. The dark resin which results is washedwith 3000 parts of boiling water then heated to 2102220 C. to dehydrate,harden and bleach. The final resin is hard, brittle, has a softeningpoint of 103 C. and an acid number of 6'1. It is very pale yellow incolor, being sub-'- stantially lighter than WW rosin.

sin. B-One mole of resorcinol is dissolved 'in two moles of methylethylketone and 5% of a 3 aqueous hydrochloric acid solution. based on thetotal weight of the mixture, is added. Th solution is heated under areflux condenser for '7 hours in which time a resinous product is formedwhich is hard'and brittle at ordinary temperatures. This is washed withwater. then heated to 200 C. to dehydrate and harden fur- The finalresin is hard, brittle and pale yellow'in color.

Resin CP-Two parts of mixed xylenols boillag between 210 C. and 225 C.are mixed with one part of a 37% aqueous formaldehyde solution, and 1 to2% of a aqueous hydrochloric acid solution, based on the total weight.01 the The mixture mixture, is added. The mixture is refluxed up to thepoint where a well defined water layer appears and heating is continuedbeyond this point until the resinous layer has thickened. The waterlayer is decanted and the soft resin heated to 230-240 C. until a sampledrop when cooled on a cold plate is hard and brittle. The final resinhas a slight phenolic odor, and is hard. brittle and lightin color.

Example 1.-The following series illustrates the results obtained withresin A, making the varnishin the (a) usual manner, and (b and c) by theprocesses of the present invention.

(a) 20 parts of resin A are mixed with parts of raw tung oil and 4 partsof linseed oil (bodied by heating at 300 C.'for 2% hours, hereafterreferred to in examples simply as bodied linseed oil). The mixture isheated at 270 C. for 10 minutes, then at 250' C. for 10 minutes,whereupon the varnish base is well bodied but not overcooked. It is thendissolved in 85 parts of V. M. 8: P naphtha and 225 parts of a 83%%solution of lead-cobalt naphthenate in V. M. I: P. naphtha (hereafterreferred to in examples simply as drier solution) are added.

as (b) 20 parts of resin A are mixed with 40 V. M. I: P. naphtha and2.25 parts of drier solution added.

(0) The process of example (b) is duplicated in every phase except thatthe batch is heated at 120? C. for 3 hours instead of 1 hour.

The solutions of varnish (a) and sieeative compositions (b) and (e) haveabout the same viscosity. When poured onto a glass plate and drained 01!to form a thin film, the film of varnish (a) dries in 6% hours: that ofvarnish (b) in 43 hours; that of varnish (e) in 5% hours. The dryingtime is recorded as the time required for a film to set sufilcientlyhard so that a strip of copper foil V inch wide Just falls to adherewhen pressed firmly against the film. After the films have air-driedfor)! days they are immersed in a 5% aqueous caustic soda solution. Thefilm of varnish (a) whitens in 15 hours and is entirely eaten away in 44hours: that of varnish (b) does not whiten until 80 hours have elapsedalthough it is destroyed in 44 hours; that of varnish (0) requires thesurprising period of hours to whiten and is not eaten away until 108hours have elapsed.

Example 2.-The following series illustrates the results obtained whenthe processes of the present invention are applied to resin 3 incontrast to a varnish made in the usual manner of varnish kettlepractice.

(a) 20 parts of resin B are mixed with 40 partsof raw tung oil and 4parts of bodied linseed oil. infested at 270' C. for 10 minutes, then at250' C. or 10 minutes, whereupon the oilresin mixture sufiieientlvboiled without being overcooked. It is then cooled, dissolved in Partsof V. M. P. drier solution a ded.

(b) 20 parts of resin B are mixed with 40 parts of raw tung oil, 4 partsof bodied linseed oil and 1 part of oxalic acid. The mixture is heatedat naphtha and 2.25 parts of C. for 1 hour, then the temperature is rap-I idly carried to 260 C. to remove the oxalic acid by volatilization ordecomposition. As soon as 7 days,

the temperature reaches 260 C.,- the product is cooled, dissolvedin 65parts of V. M. 8: P. naphtha and 2.25 parts of drier solution added.

(c) The process of example (b) is duplicated in every phase except thatthe mixture isheated at 120 C. for 3 hours instead of 1 hour.

The varnish solutions of '(a), (b) and (c) all have about the sameviscosity and color. When they are poured on glass plates and drained toform a thin film, all dry in 3 hours. After drying 7 days, they areimmersed in a aqueous caustic soda solution. The film from varnish (a)is entirely destroyed in 11 hours; that from varnish (b) is notdestroyed until 23 hours have elapsed; that from varnish (c) is onlyafiected in places after 39 hours.

Example 3.--The following series illustrates the process of the presentinvention applied to resin C in contrast to an ordinary varnish kettlevarnish made with the same resin.

(a) 20 parts of resin C are mixed with 40 parts of raw tung oil and 4parts of bodied linseed oil. The mixture is heated at 270 C. forminutes, cooled, thinned with 65 parts of V. M. & P. naphtha and 2.25parts of drier solution.

(b) parts of resin C are mixed with 40 parts of raw tung oil, 4 parts ofbgdied linseed oil and 1 part of oxalic acid. The mixture is heated at120 C. for 1 hour, then the temperature is raised abruptly to 260 C. toeliminate oxalic acid sufliciently. As soon as the temperature reaches260 C., the product is cooled,- dissolved in 65 parts of V. M. & P.naphtha and 2.25 parts of drier solution added.

(0) The process of example (17) is duplicated, except that the mixtureis heated at 120? C. for 3 hours instead of 1 hour.

The varnish solutions (a), *(b) and (e) have about' the same viscosityand color. When poured on glass plates and drained to form thin films,the film from varnish (a) dries in 5% hours; that from varnish (b) in 5hours; that from varnish (c) in 4% hours. After drying for if they areimmersed in a 5% aqueous the film from varnish (a) is destroyed in 18hours;

whitens after 20 hours caustic soda solution whitens in 8 hours and thatfrom varnish (b) immersion and is destroyed only after 40 hours haveelapsed; that from varnish (0) requires the exceptionally long time of50 hours to whiten and is only destroyed after 90 hours.

Example 4.-20 parts of resin A are mixed with 40 parts of raw tungoiland 2 parts of oxalic acid. The mixture is heated minutes, then up to278 C. over a period of 8 minutes. When the temperature reaches 273 C.,the product is immediately cooled by dissolving it in 60 parts of V. M.8: P. naphtha. 2.1 parts of drier solution are added and a film pouredon a glass plate. The film driesto touch in 4 /2 hours and when dry,shows no wrinkling, frosting or crow-footing even in the thickerportions. After drying for 44 hours, it is immersed in a 5% aqueouscaustic soda solution. The film shows excellentadhesion and only whitensslightly around the edges after 96 hours immersion.

270 C. and held at Example 5.-40 parts of resin A are mixed with 70parts of raw tung oil, 10 parts of bodied linseed oil and 2 parts ofoxalic acid. The mixture is heated at 110-115 C. for 1- hour, then up tothe latter temperature for 5 oxalic acid and thicken the minutes, toremove tl ren cooled, dissolved in product further. It is at 139-140 C.for

140 parts of V. M. 8: P. naphtha and 3.6 parts of drier solution added.

The varnish is poured on a glass plate and drained off to form a thinfilm. The film sets to touch in 2 hours and 50 minutes and fails toadhere to copperfoilin 3 hours and 50 minutes. Without drier the varnishsets to touch in 2 hours and 50 minutes and dries hard overnight. Upondrying a film does not frost, crow-foot, or wrinkle.

If 1.8 parts of drier solution are added to thevarnish instead of 3.6parts as given above, a film just fails to adhere to a strip of copperfoil in 4 hours and 45 minutes and is hard so that considerable pressureof the thumb will not leave a print when dried in 21 hours.

Example 6.-50 parts of raw tung oil are mixed with 25 parts of resin Aand heated to 120-130 C. While being mechanically stirred 0.1 part of aaqueous hydrochloric acid solution is added and heating continued for 45minutes. The temperature is then raised to 260 C. to remove the acid.The thickened reaction mixture is thinned with 75 parts of V. M. & P.naphtha and 2.63 parts of drier solution added. The varnish is ratherdark in color, but dries to touch to a comparatively light-colored,wrinkle-free film in about 4 hours.

Example 7.-50 parts of raw tung oil are mixed with 25 parts of resin Aand 1.5 parts of dichloracetic acid, and heated for 30 minutes at 130 C.The temperature is then raised to 260 C. to eliminate the dichloraceticacid, the thickened reaction product thinned with 75 parts of V. M. & P.naphtha and 2.63 parts of drier solution added. The varnish is somewhatdark in to 200 C. until the resin dissolves, then cooled to "130 C. and4 parts of sodium bisulphate added.

C. for about 3 hours v Heating is continued at 130 until the mixturesubstantially thickens. It is then thinned with 80 parts of V. M. &-P.naphthe. and the sediment of sodium blsulphate filtered ofi. Driers areadded and a film poured which dries to a non-wrinkled surface.

Thus acid salts may also be used in the present invention in placeHowever, it is best to use those salts ,which are readily soluble in thedrying oil-resin mixture. I may also use neutral salts, 'as'for example,ammonium oxalate, or compounds which generate acids upon heating. I

In general it is desirable to remove all traces of the acid condensingagent from the reaction product in order to secure rapid drying. Thismay be accomplished by heating the reaction product after reactionrapidly to a comparatively high temperature, thencooling quickly andthinning, or only a partial reaction maybe secured at a low temperaturefollowed by a prolonged heating at a higher temperature. If oxalic acidis employed as the catalyst, a primary reaction may be effected at110-l20 C. until a definite of acid condensing agents..

thickening has occurred, then thetemperature the siccative base in wateruntil the wash'water is neutral to litmus and the entrained waterremoved under a vacuum, or the product heated above C. until foaming andbubbling cease. In the examples, soluble naphthenate driers were addedto the varnishes after they had been thinned and cooled. However, thisis not necessary, but the salts of lead, cobalt and/or man ganese may beadded directly to the hot varnish melt, or in some cases the drier maybe omitted.

I have described the use of reactive unsaturated fatty oils in thisinvention but the unsaturated acid derived from unsaturated fatty oilsmay be employed and subsequently esterified, if desired.

The use of a catalyst is indispensable to the present process. As anexample, 1 part of resin A is heated with 2 parts of raw tung oil at C.for about 30 hours. Little or no thickening of the mixture takes placein this time and the resin precipitates from the oil upon addition of V.M. & P. naphtha. If, however, 0.1 to 0.06 part of oxalic acid is addedand heated to 120 C., thickening takes place in about 5 minutes. On theother hand, if 0.1 to 0.06 part of oxalic acid is heated to 120 C. in 2parts of raw tung oil for 40 hours, little or no thickening takes place,indicating that the catalyst has little or no polymerizing orgelatinizing eifect upon the tung oil at that temperature. The-varnishreaction products may be thinned with petroleum solvents, such as V. M.& P. naphtha or hydrosolvents, such as that known to the trade asSolvesso, or other solvents, such as toluol, xylol, turpentine, and thelike, or mixtures of these solvents. Mineral spirit soluble driers, suchas lead and cobalt naphthenates, resinates, and so forth, may beemployed or the driers may be cooked directly into the resin-oilreaction product in the form of salts of lead, cobalt and/or manganese.

The temperatures indicated above for the primary reaction of resin andoil, that is, 90-160 C., are the preferred temperatures. Temperatureshigher than 160 C. and lower than 90 C. may be used but for the mostsatisfactory results when employing oxalic acid as the catalyst therange from 90 to 160 C. is entirely satisfactory. Temperatures lowerthan 90 C. necessitate an extremely long heating of the oil-resinmixture in order to bring about reaction when catalytic amounts ofoxalic acid are used and temperatures higher than 160 C. are undesirablesince oxalic acid sublimes from the reaction mixture at a rapid rate,requiring frequent replenishing of the acid. Temperatures of 110-140 0.give the smoothest reaction, that is, one which proceeds evenly withoutrapid gelling or local polymerization which would result in a lumpycomposition. With acids other than oxalic acid difl'erent temperaturesmay be used as dictated by the characteristics of the acid. Therefore itis understood that when the temperature range of 90 to 160 C. isindicated I imply the employment of oxalic acid or its equivalent. Otheracid catalysts may require a diiferent temperature range. Thetemperatures used in the present invention for primary reaction of aphenolic resin witha drying oil in the presence of a catalyst are farbelow those used in ordinary varnish kettle practice. For instance, iftemperatures of 90 to 160 C. or even 160 to 200 C. are used in the usualvarnish kettle practice of making varnishes, extremely long cookingperiods would be required and the resulting varnish would, in general,be poor in water, acid, alkali and weather resistance. If heated at -200C. for the same period usually used at the usual higher varnish makingthe oil-resin mixture.

temperatures, the varnish would be poor in body and mineral spiritsolubility, as well as having relatively no resistance to meclianicaland chemical agents. Furthermore, when made from tung oil the lattervarnishes would have a tendency to dry to a frosted or wrinkled surface.Varnish kettle practice usually demands temperatures of 250 C. andhigher.

To recapitulate, the process of the present invention comprises reactingan oil-soluble phenolic resin with a drying oil at a relatively lowtemperature in the presence of an acid condensing agent to providesiccative compositions capable of yielding substantially alkali, acid,water and weather resistant films.

The varnishes made by the process of this in vention are more durable asindicated by alkali resistance than the varnishes made in the usualmanner of varnish making, P ssibly since a better combination of the oiland resin is secured. In the usual varnish kettle practice, thickeningof, for example, an oil-soluble phenolic resin mixture to a large degreemay be assumed to be due to polymerization of the drying oil itself. Inthe present process, however, at the temperatures used little or nopolymerization of the drying oil itself would be likely to take placebut the thickening observed may be attributed to substantially areaction of the resin with the drying oil. In any event, the products ofthe present invention are new and distinct from those resulting merelyfrom heating the resin and oil together'in the usual manner. This isclearly indicated from the facts that the varnish compositions of thepresent invention exhibit greatly increased alkali resistance over thosemade by cooking an oil and resin together at a high temperature. If thefinal products were the same in both instances the siccativecompositions of the present invention would not show this increasedalkali resistance.

As used in the claims the term phenolic resin has reference to theso-called "100 per cent phenolic resin, 1. e., a resin which does notcontain rosin, ester gum and other solubilizing natural resins or gums.I

What I claim is: a

1. A tung oil containing varnish manufactured by cooking tung oil andanother drying oil with a normally oil-soluble phenolic-aldehyde resinin the usual varnish kettle practice, except that a small amount ofoxalic acid ing operation, the temperatures employed are substantiallybelow 200 C., a final brief heating to a top temperature of about 270(3., being employed as a step in the process to eliminatev oxalic ingoil with an oil soluble phenolic aldehyde resin at a temperature withinthe range of from 90 C. to C. in the presence of a small amount of anacid catalyst to body the oil and resinous composition sufliciently forvarnish purposes, which composition is'soluble in the usual varnishthinners to give a clear varnish, and which varnish is adapted to airdry in a few hours when applied to a surface in the form of a film andwhich dried film is highly resistant to alkali.

3. An oil varnish consisting of a drying oil containing conjugateddouble bonds, a resin, varnish thinners and driers produced by heatingthe drying oil with an oil soluble phenolic aldehyde resin is includedin the 1 mixture of oil and resin during the heat bodyat a temperaturewithin the range of from 90 C. to 160 C. in the presence of oxalic acidto produce a thickened oil and resinous composition which is soluble inthe usual varnish thinners to form a clear varnish adapted when appliedto a surface in the form of a film to air dry in about 3 to 5 hours, andwhich film is highly alkali resistant.

v 4. An oil varnish adapted to air-dry produced by cooking attemperatures substantially below 200 C., a mixture consisting of adrying oil containing conjugated double bonds, a normally oil solublephenolic aldehyde resin and a small amount of one of the class of acidsconsisting of dichloracetic acid, oxalic acid, phosphoric acid,hydrochloric acid, p-toluene sulphonic acid, sulphuric acid andmonochloracetic acid, until the oil is bodied sufliciently for varnishpurposes, and

thereafter thinning with varnish solvents and adding driers.

5. A tung oil containing varnish adapted to air-dry in a few hours to afrost-free, non-crowfooted. non-wrinkled film produced by cooking attemperatures within the range of from 90 C.

to 160 0., a mixture consisting of tung oil a normally oil solublephenolic aldehyde resin and a small amount of one of the class of acidsconsisting of dichloracetic acid, oxalic acid, phosphorus acid,hydrochloric acid, p-toluene sul-' air-dry in a few hours to afrost-free, non-crowfooted, non-wrinkled film produced by cooking attemperatures within the range of from 90 C. to 160 C., a mixtureconsisting of tung oil, a normally oil soluble phenolic aldehyde resinand a small amount of an acid catalyst until the tung oil is bodiedsufilciently for varnish purposes, and

thereafter thinning with varnish solvents and adding driers.

7. The tung oil varnish set forth in claim 6, in which the acid catalystis oxalic acid. 8. An oil varnish adapted to air-dry, produced bycooking at temperatures within the range of from 90 C. to 160 C., amixture consisting of a drying oil containing conjugated double bonds, anormally oil soluble phenolic resin and a small amount of an acidcatalyst until the oil is bodied sumciently for varnish purposes, andthereafter thinning with varnish solvents and adding driers.

. JOHN B. RUST.

